468984 Engineered Photocrosslinkable Protein Coatings Improve Osseointegration of Orthopaedic Implants

Monday, November 14, 2016
Grand Ballroom B (Hilton San Francisco Union Square)
Christopher Lindsay1, Jordan Raphel1, Johan Karlsson2, Silvia Galli3, Ann Wennerberg3, Matthew Haugh1,4, Jukka Pajarinen5, Stuart Goodman5, Ryo Jimbo3,6, Martin Andersson2 and Sarah C. Heilshorn1, (1)Materials Science and Engineering, Stanford University, Stanford, CA, (2)Chemistry and Chemical Engineering, Chalmers University, Gothenburg, Sweden, (3)Department of Prosthodontics, Faculty of Odontology, Malmö University, Malmö, Sweden, (4)Mechanical Engineering and Biomedical Engineering, Royal College of Surgeons in Ireland, Dublin, Ireland, (5)Department of Orthopaedic Surgery, Stanford University, Stanford, CA, (6)Department of Oral and Maxillofacial Surgery and Oral Medicine, Faculty of Odontology, Malmö University, Malmö, Sweden

As the U.S. population continues to age, the use of orthopedic implants is projected to grow rapidly in the coming decades. With failure rates of orthopedic implants around 10%, combined with the millions of new implants a year, implant failures will lead to an ever-increasing burden on patients and the healthcare system. Developing new technologies to improve the long-term osseointegration of orthopaedic implants to prevent premature failure is paramount in addressing the growing cost of implant failures. We present an elastin-like engineered protein (ELP) material that incorporates a bioactive RGD sequence to promote osteoblast and mesenchymal stem cell (MSC) adhesion to facilitate rapid bone growth and implant integration. The recombinant ELP polymer is covalently modified with a photocosslinkable moiety to enable facile spin-coating or dip-coating of any implant geometry prior to covalent crosslinking to form a stable coating on the implant surface. ELP coatings are shown to remain intact after implants have undergone simulated dental and orthopaedic insertion and removal. Using the MG63 osteoblast-like cell line, ELP coated implants showed 80% adhesion of cells after 24 hours compared to 38% for an uncoated Ti6Al4V sample. Additionally, MG63s showed a significant increase in bone mineral deposition at all time points up to two weeks, demonstrating the osseointegrative capabilities of the coating. Human mesenchymal stem cells (hMSCs) similarly showed an increase in bone mineral deposition on ELP implant surfaces compared to uncoated controls. The ELP coating also accelerated hMSC differentiation into osteoblast-like lineages, as evident by a spike in alkaline phosphotase activity at 7 days, compared to 14 days for the control. Finally, our coatings improve functional recovery of dental implants, as demonstrated by a significant increase in removal torque of ELP coated implants after one week. We have shown an increase in key in vitro markers that point to early osseointegration of ELP coated implants, and verified that through functional recovery tests. By engineering a bioactive peptide sequence into a durable protein coating for orthopaedic implants, we have been able to create a more favorable microenvironment for tissue regeneration and implant recovery.

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